Process of producing rayon



Patented June 1, 1948 PROCESS OF PRODUCING RAYON Arthur Cressweli,Elizabethton, Tenn, assignor to North American Rayon Corporation, NewYork, N. 1., a corporation of Delaware No Drawing. Application March 7,1940, Serial No. 322,755

30 Claims. (01. 18-54) tions when a viscose solution is extruded into anacid spin bath to form filaments, threads,

yarns, ribbons and the like.

In the commercial production of viscose rayon it is necessary forreasons of economy to provide for uninterrupted spinning of even denierfilaments. Interruption of spinning is generally caused by thecontamination of the spinnerets themselves due to various impurities inthe viscose solution and/or the spin bath. These impurities have atendency to agglomerate or deposit on the spinneret and thus to closegradually its fine orifices. Zinc rings, calcium rings, sulphur craters,precipitated cellulose, resin particles, secondary reaction products,etc., are impurities which cause spinneret incrustations. The spinneretsare especially susceptible to incrustation when acid spin baths are usedcontaining dissolved zinc salts such as for example zinc sulphate.Sulphuric acid is conventionally used in viscose spin baths. Even if thedeposit of impurities is insuflicient to entirely close the spinneretorifices, it causes variations in the denier and cross sections of thefilaments which in turn impart undesirable properties to the finishedviscose products. Also, so-called spinning hooks tend to form at theobstructions, either in or around the orifices of the spinneret, which,when filaments are extruded therethrough, will tend to cause a temporaryinterruption of the spinning of a filament at the orifice affected, thusoccasioning tearing of the filament. These deficiencies necessitatefrequent and expensive spinneret changes and cause an increase in lowerquality yarns.

Although incrustation of spinnerets is especially noticeable when metalspinnerets made from gold, gold-platinum, gold-palladium,platinumrhodium, tantalum, or any other corrosion-resistant metal, areused, this deficiency is also experienced with spinnerets manufacturedfrom artificial ruby and other semi-precious stones. The prevention ofincrustation is becoming more and more important with the increasingtendency in the art to spin finer denier filaments which necessitatesthe use of smaller orifices.

I am well aware that it has, heretofore, been proposed to prevent theclogging of spinneret orifices by adding cation-active compounds to thespin bath or viscose solution (vide U. S. Patent No. 2,125,031 to Polakand Weeldenburg issued on July 26, 1938, and U. S. Patent No. 2,132,929to Bley issued on October 11, 1938), or by coating the spinnerets withwax-like materials (vide U. S. Patent No. 2,100,581 to Weeldenburgissued on November 30, 1937). By extensive experiments I haveunexpectedly found that the incrustation of spinneret orifices issubstantially prevented by water-soluble polymerization products ofalkylene oxides or substitution products thereof which products becomecation-active in acid spinning baths used in the coagulation of viscosethread. In order to be operative they must have at least a limitedsolubility and stability in acid spin baths and/or viscose solutions,

While I have found that under certain optimum conditions extremely smallquantities of these polymers efiect the desired result when added to thespin bath, the viscose solution or both, and that 0.0001% of suchcompounds has been found sufflcient, generally 1 have ascertained thatthe addition thereof in a considerable excess of 0.05% should be avoidedfor reasons of economy. I prefer to use an addition of about 0.005%based on the active ingredient of the chosen compounds. Although thesepolymerized alkylene oxides, etc., may be added either to the spin bathor the spinning solutions, it is preferred that they be added to thespin baths, for the reason that it is now common practice to regeneratespin baths and thereby avoid losses of the constituents thereof.

Polymerized alkylene oxides, adapted to be used in combination withviscose solutions and/or acid spin baths, may be prepared in accordancewith processes set forth in British Patent No. 346,550, German PatentNo. 597,496, and French Patent No. 7 50,520, issued to I. G.Farbenindustrie A. G. 'The degree of polymerization of alkylene oxidesmay be varied to a large extent by varying the conditions under whichpolymerization is induced, and I have found that polymers of alkyleneand ethylene oxides having a degree of polymerization above 30 areespecially useful for preventing spinneret incrustations provided theyare sufficiently soluble and stable in spin baths and/or viscosesolutions. The alkylene oxides adapted to be polymerized have thestructure Ron in which R represents hydrogen, an alkyl, a cycloal yl oran aryl radical.

The following examples will serve to illustrate my present invention:

Example I A conventional viscose solution was spun into a well-knownacid spin bath containing sulphuric acid, sodium sulphate, magnesiumsulphate and a small quantity of zinc sulphate. When about 0.005% of apolymerized ethylene oxide having a polymerization degree of about 91(manufactured under the trade name "Wax 4000" by Carbide and CarbonChemicals Corp., New York, N, Y.) was added, calculated on the spinbath, most of the irregularities and difiiculties in spinning wereeliminated during a long run.

Example 11 The surface-active compound, set forth in Example I, wasadded to a conventional viscose solution before spinning, and itinhibited the formation oi incrustation of the spinneret through whichthe solution was extended to form viscose rayon during a long run.

Example III The surface-active compound set forth in Example I was addedto both the spin bath-and the viscose solution and it inhibited theformation of incrustation on the spinnerets for a relatively long periodof time.

Examples of other suitable polymerized alkylene oxides are: polyethyleneoxide having a polymerization degree of about 34 (manufactured under thetrade name "Carbowax 1500 by Carbide and Carbon Chemicals Corp., NewYork, N. Y.) polymerized propylene oxides, nonaethylene glycol, etc.

The viscose solution to be extruded through the orifices of a spinneretmay contain additional compounds such as delustrants, proteins (casein),etc. Since in the spinning of high strength yarns, i. e., yarns having adry strength of at least 2 grams per denier, such as those used in tireconstructions and mechanical rubber goods (belts, hose, etc.) and in thewell-known continuous spinning processes, the contamination of thespinnerets is particularly serious, this invention is of specialimportance in this field. I have, furthermore, found by experimentationthat polymerized alkylene oxides, for example, polyethylene oxides whichare not only sufficiently soluble and stable in acid spin baths but"which in addition are capable of precipitating negatively chargedcolloidal particles occurring as contaminations in the spin bath, suchas for example, colloidal sulphur particles prevent the clogging ofspinneret orifices more efiectively than alkylene oxides which do notprecipitate negatively charged particles. Modifications of my processwill readily be recognized by those skilled in the art, and I desire toinclude all such modifications and variations coming within the scope ofthe appended claims. In these claims the term alkylene oxide is intendedto cover ethylene oxide per se, its homologues (for example, propyleneoxide, etc.) and substitution products thereof.

Iclaim:

1. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acidprecipitating bath to form filaments and the like therefrom,

the step which comprises spinning the viscose filaments in the presenceof a very small amount of a dissolved, substantially stable.surface-active polymerized ethylene oxide, whereby incrustation of thespinneret during the spinning operation is substantially inhibited.

2. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a corrosion-resistant metalspinneret into an acid precipitating bath to form filaments and the liketherefrom, the step which comprises spinning the viscose filaments inthe presence of a very small amount of a dissolved, substantially stablesurface-active polymerized ethylene oxide, whereby incrustation of thespinneret during the spinning operation is substantially inhibited.

3. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a platinum alloy spinneret into anacid precipitating bath to form filaments and the like therefrom thestep which comprises spinning the viscose filaments in the presence of asmall amount of a dissolved, substantially stable, surface activepolymerized ethylene oxlde, whereby incrustation of the spinneret duringthe spinning operation is substantially inhibited.

4. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acid,zinc-containing precipitating bath to form filaments and the liketherefrom, the step which comprises spinning the viscose filaments inthe presence of a very small amount of a dissolved, substantiallystable, surface-active polymerized ethylene oxide, whereby incrustationof the spinneret during the spinning operation is substantiallyinhibited.

5. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a corrosion-resistant metalspinneret into an acid, zinc-containing precipitating bath to formfilaments and the like therefrom, the step which comprises spinning theviscose filaments in the presence of a very small amount of a dissolved,substantially stable, surface-active polymerized ethylene oxide, wherebyincrustation of the spinneret during the spinning operation issubstantially inhibited.

6. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a platinum alloy spinneret into anacid, zinc-containing precipitating bath to form filaments and the liketherefrom, the step which comprises spinning the viscose filaments inthe presence of a small amount of a dissolved, substantially stable,surface-active polymerized ethylene oxide, whereby incrustation of thespinneret during the spinning operation is substantially inhibited. I

7. In the manufacture of a viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acid, zincsulphatecontaining precipitating bath to form filaments and the liketherefrom, the step which comprises spinning the viscose filaments inthe presence of a very small amount of a dissolved, substantiallystable, surface-active polymerized ethylene oxide, whereby incrustationof the spinneret during the spinning operation is substantiallyinhibited.

8. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a corrosion-resistant metalspinneret into an acid, zinc sulphate-containing precipitating bath toform filaments and the like therefrom, the step which comprises spinningthe viscose filaments in the presence of a very small amount of adissolved, substantially stable. surface-active polymerized ethyleneoxide, whereby incrustatlon of the spinneret during the spinningoperation is substantially inhibited.

9. A viscose spin bath, for coagulating viscose filaments thereincontaining a small amount of a dissolved, substantially stable,surface-active polymerized ethylene oxide.

10. A viscose spin bath, for coagulating viscose filaments therein,containing a dissolved zinc salt and a small amount of a dissolved,substantially stable, surface-active polymerized ethylene oxide.

11. A viscose spin bath, for coagulating viscose filaments therein,containing zinc sulphate and a small amount of a dissolved,substantially stable, surface-active polymerized ethylene oxide.

12. A viscose solution containing a small amount of a dissolved,substantially stable, surface-active polymerized ethylene oxide.

13. A viscose solution containing about 0.0001 to 0.05% by weight of adissolved, substantially stable, surface-active polymerized ethyleneoxide.

14. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acidprecipitating bath to form filaments and the like therefrom, the stepwhich comprises spinning the viscose filaments in the presence of a verysmall amount of a dissolved, substantially stable, surface-activepolymerized alkylene oxide, whereby incrustatlon of the spinneret duringthe spinning operation is substantially inhibited.

15. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a corrosion-resistant metalspinneret into an acid precipitating bath to form filaments and the liketherefrom, the step which comprises spinning the viscose filaments inthe presence of a very small amount of a dissolved, substantiallystable, surface-active polymerized alkylene oxide, whereby incrustationof the spinneret during the spinning operation is substantiallyinhibited.

16. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a platinum alloy spinneret into anacid precipitating bath to form filaments and the like therefrom, thestep which comprises spinning the viscose filaments in the presence of asmall amount of a dissolved, substantially stable, surface-activepolymerized alkylene oxide, whereby incrustation of the spinneret duringthe spinning operation is substantially inhibited.

17. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acid,zinc-containing precipitating bath to form filaments and the liketherefrom, the step which comprises spinning the viscose filaments inthe presence of a very small amount of a dissolved, substantiallystable, surface-active polymerized alkylene oxide, whereby incrustationoi the spinneret during the spinning operation is substantiallyinhibited.

18. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acidprecipitating bath to form filaments and the like therefrom, the stepwhich comprises spinning the viscose filaments in the presence of a verysmall amount of a dissolved, substantially stable, surface-activepolymerized alkylene oxide, whereby incrustatlon or the spinneret duringthe spinning operation is substantially inhibited, said alkylene oxidehaving a polymerization degree above 30.

19. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acidprecipitating bath to form filaments and the like therefrom, the stepwhich comprises spinning the viscose filaments in the presence of a verysmall amount of a dissolved, substantially stable, surface-activepolymerized ethylene oxide, whereby incrustatlon of the spinneret duringthe spinning operation is substantially inhibited, said ethylene oxidehaving a polymerization degree above 30.

20. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acidprecipitating bath to form filaments and the like therefrom,

the step which comprises spinning the viscose filaments in an acidprecipitating bath containing a small amount of a dissolved,substantially stable, surface-active polymerized ethylene oxide.

21. In the manufacture of viscose yarn wherein a viscose solution isextruded through minute orifices of a spinneret into an acidprecipitating bath to form filaments and the like therefrom, the stepwhich comprises spinning the viscose filaments by extrusion of a viscosesolution containing a small amount of a dissolved, substantially stable,surface-active polymerized ethylene oxide.

22. A viscose spin bath, for coagulating viscose filaments therein,containing a small amount of a. dissolved, substantially stable,surface-active polymerized alkylene oxide.

23. A viscose spin bath, for coagulating viscose filaments therein,containing a dissolved zinc salt and a small amount of a dissolved,substantially stable, surface-active polymerized alkylene oxide.

24. A viscose spin bath, for coagulating viscose filaments therein,containing zinc sulphate and a small amount of a dissolved,substantially stable, surface-active polymerized alkylene oxide.

25. A viscose spin bath comprising water, sulphuric acid, zinc sulphateand about 0.0001 to 0.05% by weight of a dissolved, substantiallystable, surface-active polymerized alkylene oxide.

26. A viscose spin bath comprising water, sulphuric acid, zinc sulphateand about 0.0001 to 0.05% by weight of a dissolved, substantiallystable, surface-active polymerized ethylene oxide.

27. A viscose solution containing a small amount of a dissolved,substantially stable, surface-active polymerized alkylene oxide.

28. A viscose solution containing a small amount of a dissolved,substantially stable, surface-active polymerized alkylene oxide having apolymerization degree above 30.

29. A viscose solution containing a small amount of a dissolved,substantially stable, surface-active polymerized ethylene oxide having apolymerization degree above 30.

30. A viscose solution containing about 0.0001 to 0.05% by weight of adissolved, substantially stable, surface-active polymerized alkyleneoxide.

ARTHUR CRESSWEIL.

REFERENCES CITED The following references are of record in the file ofthis patent:

' STATES PATENTS Number

